In passenger cars according to the general state of the art, hydraulic fluid (=pressure medium) is pressurized in the pressure chambers of the brake master cylinder by a brake master cylinder force as a result of a brake pedal actuation by the driver, which force is composed, in a ratio of 1 to V−1, from an actuating force component exerted by the driver and a boosting force component exerted by the brake booster. In passenger car brake systems the force boosting factor V is usually between 3 and 7, in most passenger cars approximately 4. That is to say that upon actuation of the brake pedal for activating the friction brakes of an average passenger car, 4/5 of the master cylinder pressure is generated by the brake booster and only 1/5 by the driver via the brake pedal. This has the agreeable effect that passenger car brake systems can be operated with moderate pedal forces.
An electrohydraulic brake system of the type mentioned in the introduction is described in DE 10 2006 060 434 A1. In the known brake system it is proposed, in order to simulate in recuperation braking the brake pedal characteristic known from normal braking, not to conduct the hydraulic fluid pressurized in the brake master cylinder to the wheel brakes but to take up same in a cylinder-piston arrangement. In this case it is felt to be disadvantageous that 4/5 (where V=4, otherwise a proportion V/(1+V)) of the pressure values exerted, and the associated take-up of pressure medium, are unnecessary. During recuperation braking no brake boosting is required.